Microelectronic devices and methods for manufacturing microelectronic devices

ABSTRACT

Microelectronic devices and methods for manufacturing microelectronic devices are disclosed herein. In one embodiment, a microelectronic device includes a microelectronic die, a plurality of electrical couplers projecting from the die, and a flowable material disposed on the die. The die includes an integrated circuit and a plurality of terminals operably coupled to the integrated circuit. The electrical couplers are attached to corresponding terminals on the die. The flowable material includes a plurality of spacer elements sized to space the die apart from another component. The flowable material may be a no-flow underfill, a flux compound, or other suitable material.

TECHNICAL FIELD

The present invention is related to microelectronic devices and methodsfor manufacturing microelectronic devices.

BACKGROUND

Microelectronic devices generally have a die (i.e., a chip) thatincludes integrated circuitry having a high density of very smallcomponents. In a typical process, a large number of dies aremanufactured on a single wafer using many different processes that maybe repeated at various stages (e.g., implanting, doping,photolithography, chemical vapor deposition, plasma vapor deposition,plating, planarizing, etching, etc.). The dies typically include anarray of very small bond-pads electrically coupled to the integratedcircuitry. The bond-pads are the external electrical contacts on the diethrough which the supply voltage, signals, etc., are transmitted to andfrom the integrated circuitry. The dies are then separated from oneanother (i.e., singulated) by dicing the wafer and backgrinding theindividual dies. After the dies have been singulated, they are typically“packaged” to couple the bond-pads to a larger array of electricalterminals that can be more easily coupled to the various power supplylines, signal lines, and ground lines.

One type of microelectronic device is a “flip-chip” semiconductordevice. These devices are referred to as “flip-chips” because they aretypically manufactured on a wafer and have an active side with bond-padsthat initially face upward. After manufacture is completed and a die issingulated, the die is inverted or “flipped” such that the active sidebearing the bond-pads faces downward for attachment to a substrate. Thebond-pads are usually coupled to terminals, such as conductive “bumps,”that electrically and mechanically connect the die to the substrate. Thebumps on the flip-chip can be formed from solders, conductive polymers,or other materials. In applications using solder bumps, the solder bumpsare reflowed to form a solder joint between the flip-chip component andthe substrate. This leaves a small gap between the flip-chip and thesubstrate. To enhance the integrity of the joint between the die and thesubstrate, an underfill material is introduced into the gap. Theunderfill material bears some of the stress placed on the components andprotects the components from moisture, chemicals, and othercontaminants. The underfill material can include filler particles toincrease the rigidity of the material and modify the coefficient ofthermal expansion of the material.

Electronic products require packaged microelectronic devices to have anextremely high density of components in a very limited space. Forexample, the space available for memory devices, processors, displays,and other microelectronic components is quite limited in cell phones,PDAs, portable computers, and many other products. As such, there is astrong drive to reduce the surface area or “footprint” of amicroelectronic device on a printed circuit board. Reducing the size ofa microelectronic device is difficult because high performancemicroelectronic dies generally have more bond-pads, which result inlarger ball-grid arrays and thus larger footprints. One technique usedto increase the density of microelectronic dies within a given footprintis to stack one microelectronic die on top of another. For example, FIG.1A schematically illustrates a conventional microelectronic device 4including a first microelectronic die 10 a, a second microelectronic die10 b stacked on top of the first die 10 a, an interposer substrate 60carrying the first and second dies 10 a-b, a plurality of first solderbumps 20 a between the first die 10 a and the substrate 60, and aplurality of second solder bumps 20 b (only one shown) between the firstand second dies 10 a-b. FIG. 1B schematically illustrates themicroelectronic device 4 after reflowing the first and second solderbumps 20 a-b to mechanically and electrically connect the first die 10 ato the substrate 60 and the second die 10 b to the first die 10 a,respectively.

One drawback of the conventional microelectronic device 4 illustrated inFIGS. 1A and 1B is that during reflow the weight of the dies 10 a-b maycause the heated solder bumps 20 a-b to collapse such that the dies 10a-b move toward the substrate 60 in a direction X. The collapse of thesolder bumps 20 a-b and associated movement of the dies 10 a-b can causeseveral problems. First, the solder from the bumps 20 a-b may spread toofar such that the solder from one bump 20 a-b contacts the solder froman adjacent bump 20 a-b and creates an electrical short in the device 4.Second, the downward movement of the dies 10 a-b may leave aninsufficient gap Y between the first die 10 a and the substrate 60and/or between the first and second dies 10 a-b. If the gap Y betweenthe components is too small, it is difficult to wick underfill materialinto the gap Y. Third, the downward movement of the dies 10 a-b createsvariances in the height of different devices 4, which can cause problemswith molding, testing, and other post-reflow processes that requireknown device heights. Fourth, when the solder bumps 20 b are positionedalong only a central portion of the die 10 b (e.g., memory dies), thesecond die 10 b may tilt after reflow. Die tilt can also cause problemswith molding, testing, and other post-reflow processes. For example, ifthe second die 10 b is not parallel to the first die 10 a, the “highside” of the second die 10 b may be exposed after encapsulation.Accordingly, there is a need to improve the process of packaging dies inmicroelectronic devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A schematically illustrates a conventional microelectronic devicein accordance with the prior art.

FIG. 1B schematically illustrates the conventional microelectronicdevice of FIG. 1A after reflowing the solder bumps.

FIGS. 2A-2C illustrate stages in one embodiment of a method formanufacturing a plurality of microelectronic devices in accordance withthe invention.

FIG. 2A is a schematic side cross-sectional view of a portion of amicrofeature workpiece including a substrate and a plurality ofmicroelectronic dies formed in and/or on the substrate.

FIG. 2B is a schematic side cross-sectional view of a microelectronicdevice assembly including a plurality of singulated dies arranged in anarray on a support member.

FIG. 2C is a schematic side cross-sectional view of the microelectronicdevice assembly after reflowing the electrical couplers to mechanicallyand electrically connect the terminals to the contacts.

FIGS. 3A-3E illustrate stages in another embodiment of a method formanufacturing a plurality of microelectronic devices in accordance withthe invention.

FIG. 3A is a top plan view of a microfeature workpiece.

FIG. 3B is a schematic side cross-sectional view of the workpiece takensubstantially along line 3B-3B in FIG. 3A.

FIG. 3C is a schematic side cross-sectional view of the workpiece afterforming an underfill layer on the dies.

FIG. 3D is a schematic side cross-sectional view of a microelectronicdevice assembly including a plurality of singulated microelectronic diesarranged in an array on a support member.

FIG. 3E is a schematic side cross-sectional view of the microelectronicdevice assembly after reflowing the electrical couplers to mechanicallyand electrically connect the terminals to the contacts.

FIG. 4A is a schematic top plan view of a microfeature workpiece inaccordance with another embodiment of the invention.

FIG. 4B is a schematic side cross-sectional view of the workpiece takensubstantially along line 4B-4B in FIG. 4A.

FIGS. 5A and 5B illustrate stages in another embodiment of a method formanufacturing a plurality of microelectronic devices in accordance withthe invention.

FIG. 5A is a schematic side cross-sectional view of a microelectronicdevice assembly in accordance with another embodiment of the invention.

FIG. 5B is a schematic side cross-sectional view of the microelectronicdevice assembly after reflowing the first and second electricalcouplers.

DETAILED DESCRIPTION A. Overview

The following disclosure describes several embodiments ofmicroelectronic devices and methods for manufacturing microelectronicdevices. An embodiment of one such device includes a microelectronicdie, a plurality of electrical couplers projecting from the die, and aflowable material disposed on the die. The die includes an integratedcircuit and a plurality of terminals operably coupled to the integratedcircuit. The electrical couplers are attached to corresponding terminalson the die. The flowable material includes a plurality of spacerelements sized to space the die apart from another component to whichthe die is subsequently attached. The flowable material may be a no-flowunderfill, a flux compound, or other suitable material.

In another embodiment, a microelectronic device includes (a) amicroelectronic component having an active side and a plurality ofterminals on the active side, (b) a plurality of electrical couplersattached to corresponding terminals and projecting from themicroelectronic component, and (c) a flowable material disposed on theactive side of the microelectronic component. The individual electricalcouplers have a first dimension, and the flowable material includes aplurality of spacer elements having a second dimension at least 30% ofthe first dimension.

In another embodiment, a microelectronic device includes (a) amicroelectronic component having a plurality of terminals, (b) aplurality of electrical couplers attached to corresponding terminals,(c) a substrate having a plurality of contacts coupled to correspondingelectrical couplers, and (d) a flowable material between themicroelectronic component and the substrate. The flowable materialincludes a plurality of spacer elements with at least one spacer elementcontacting the microelectronic component and the substrate. Theelectrical couplers can include a plurality of reflowed solder balls.

In another embodiment, a microelectronic device includes a firstmicroelectronic die, a second microelectronic die, and a plurality ofelectrical couplers between the first and second dies. The first dieincludes an integrated circuit, a plurality of terminals operablycoupled to the integrated circuit, and a plurality of conductiveinterconnects extending through the first die. The second die includesan integrated circuit and a plurality of terminals operably coupled tothe integrated circuit. The electrical couplers electrically connect theterminals of the second die to corresponding interconnects of the firstdie. The microelectronic device further includes a flowable materialdisposed between the first and second dies. The flowable materialincludes a plurality of spacer elements sized to space the first andsecond dies apart by a gap.

Another aspect of the invention is directed to methods for manufacturingmicroelectronic devices. An embodiment of one such method includesdepositing a flowable material onto a first microelectronic componenthaving a plurality of terminals, and attaching the first microelectroniccomponent to a second microelectronic component with the flowablematerial positioned between the first and second components and with aplurality of electrical couplers electrically connecting the terminalson the first component to corresponding contacts on the secondcomponent. The flowable material includes a plurality of spacerelements. The method further includes reflowing the electrical couplerssuch that at least one of the spacer elements contacts the first andsecond microelectronic components.

Specific details of several embodiments of the invention are describedbelow with reference to microelectronic devices with two stackedmicroelectronic dies, but in other embodiments the microelectronicdevices can have a different number of stacked dies. Several detailsdescribing well-known structures or processes often associated withfabricating microelectronic dies and microelectronic devices are not setforth in the following description for purposes of brevity and clarity.Also, several other embodiments of the invention can have differentconfigurations, components, or procedures than those described in thissection. A person of ordinary skill in the art, therefore, willaccordingly understand that the invention may have other embodimentswith additional elements, or the invention may have other embodimentswithout several of the elements shown and described below with referenceto FIGS. 2A-5B.

The term “microfeature workpiece” is used throughout to includesubstrates upon which and/or in which microelectronic devices,micromechanical devices, data storage elements, optics, and otherfeatures are fabricated. For example, microfeature workpieces can besemiconductor wafers, glass substrates, dielectric substrates, or manyother types of substrates. Many features on such microfeature workpieceshave critical dimensions less than or equal to 1 μm, and in manyapplications the critical dimensions of the smaller features are lessthan 0.25 μm or even less than 0.1 μm. Where the context permits,singular or plural terms may also include the plural or singular term,respectively. Moreover, unless the word “or” is expressly limited tomean only a single item exclusive from other items in reference to alist of at least two items, then the use of “or” in such a list is to beinterpreted as including (a) any single item in the list, (b) all of theitems in the list, or (c) any combination of the items in the list.Additionally, the term “comprising” is used throughout to mean includingat least the recited feature(s) such that any greater number of the samefeatures and/or types of other features and components are notprecluded.

B. Embodiments of Methods for Manufacturing Microelectronic Devices

FIGS. 2A-2C illustrate stages in one embodiment of a method formanufacturing a plurality of microelectronic devices in accordance withthe invention. For example, FIG. 2A is a schematic side cross-sectionalview of a portion of a microfeature workpiece 100 including a substrate108 and a plurality of microelectronic dies 110 (only two are shown)formed in and/or on the substrate 108. The individual dies 110 includean active side 112, a backside 114 opposite the active side 112, aplurality of terminals 116 (e.g., bond-pads) arranged in an array on theactive side 112, and an integrated circuit 118 (shown schematically)operably coupled to the terminals 116. Although the illustrated dies 110have the same structure, in other embodiments the dies may havedifferent features to perform different functions.

After manufacturing the microelectronic dies 110, a plurality ofelectrical couplers 120 are constructed on corresponding terminals 116and a flowable material or underfill layer 130 is formed across theworkpiece 100. The electrical couplers 120 project from the dies 110 andare conductive structures for electrically coupling the individual dies110 to other components, such as printed circuit boards or other dies.For example, the illustrated electrical couplers 120 can be solder ballsthat are “bumped” onto the dies 110 using a capillary or anothersuitable device. The underfill layer 130 protects the active side 112 ofthe dies 110 from moisture, chemicals, or other contaminants. Theunderfill layer 130 can be formed on the workpiece 100 by spin-onprocesses or other suitable processes. In the illustrated embodiment theunderfill layer 130 has a thickness D₁ greater than a diameter D₂ of theelectrical couplers 120, but in other embodiments the thickness D₁ ofthe underfill layer 130 can be less than the diameter D₂ of theelectrical couplers 120.

The illustrated underfill layer 130 includes a flowable matrix or binder132 and a plurality of spacer elements 134 disposed within the binder132. The binder 132 can include a no-flow underfill, an epoxy flux, atacky flux, or other material. For example, suitable binders 132 includeFluxFill™ FF-2300 manufactured by Henkel Technologies of Irvine, Calif.,and PK-002 Flip-Chip Epoxy Flux manufactured by Indium Corporation ofUtica, N.Y.

The spacer elements 134 are sized to provide a minimum gap between theindividual dies 110 and the corresponding external members. For example,in several applications, the spacer elements 134 may have a diameter D₃between approximately 37 μm and approximately 100 μm. In otherapplications, however, the diameter D₃ of the spacer elements 134 can beless than 37 μm or greater than 100 μm. The size of the spacer elements134 may also be based on the size of the electrical couplers 120. Forexample, the diameter D₃ of the spacer elements 134 can be betweenapproximately 30% and approximately 99% (e.g., 40%-70% and 50%-60%) ofthe diameter D₂ of the electrical couplers 120. In one such embodiment,the diameter D₂ of the electrical couplers 120 is approximately 80 μm,and the diameter D₃ of the spacer elements 134 is between approximately37 μm and approximately 50 μm. In other embodiments, the diameter D₃ ofthe spacer elements 134 can be less than 37 μm or greater than 50 μm. Ineither case, the diameter D₃ of the spacer elements 134 is less than thediameter D₂ of the electrical couplers 120 so that the electricalcouplers 120 can contact corresponding pads on the external member. Thespacer elements 134 can be glass spheres or other dielectric membersthat do not interfere with the electrical connection between theelectrical couplers 120 and the external member. After forming theunderfill layer 130, the workpiece 100 can be heated to at leastpartially cure (e.g., B stage) the underfill layer 130, and theworkpiece 100 can be cut along lines A-A to singulate the individualmicroelectronic dies 110.

FIG. 2B is a schematic side cross-sectional view of a microelectronicdevice assembly 102 including the singulated dies 110 arranged in anarray on a support member 160. The support member 160 can be a leadframe or a substrate, such as a printed circuit board, for carrying thedies 110. The illustrated support member 160 includes a first side 162with a plurality of contacts 164 and a second side 166 with a pluralityof pads 168. The contacts 164 are arranged in arrays for electricalcoupling to corresponding electrical couplers 120. The pads 168 arearranged in arrays to receive a plurality of conductive members (e.g.,solder balls). The support member 160 further includes a plurality ofconductive traces 169 electrically coupling the contacts 164 tocorresponding pads 168. The microelectronic dies 110 are placed on thesupport member 160 by pressing the underfill layer 130 against the firstside 162 of the support member 160 with the electrical couplers 120aligned with corresponding contacts 164.

FIG. 2C is a schematic side cross-sectional view of the microelectronicdevice assembly 102 after reflowing the electrical couplers 120 tomechanically and electrically connect the terminals 116 to the contacts164. During reflow, the weight of the dies 110 can cause the heatedelectrical couplers 120 to collapse such that the dies 110 move towardthe support member 160 in a direction T. Although the movement of thedies 110 spreads the underfill layer 130, at least some of the spacerelements 134 are sandwiched between the active side 112 of the dies 110and the first side 162 of the support member 160. These spacer elements134 inhibit further movement of the dies 110 in the direction T to spacethe dies 110 apart from the support member 160 by a gap G₁, which isgenerally equal to the diameter D₃ of the spacer elements 134. In otherembodiments, however, the electrical couplers 120 may not completelycollapse during reflow and the gap G₁ may be greater than the diameterD₃ of the spacer elements 134. After reflowing the electrical couplers120, a casing 170 can be formed over the dies 110, a plurality ofelectrical members 180 (e.g., solder balls) can be attached tocorresponding pads 168, and the assembly 102 can be cut along lines B-Bto singulate a plurality of individual microelectronic devices 104.

One feature of the microelectronic devices 104 illustrated in FIG. 2C isthat the spacer elements 134 space the dies 110 apart from the supportmember 160 by a predetermined distance selected to prevent the weight ofthe dies 110 from completely collapsing the electrical couplers 120during reflow. An advantage of this feature is that the microelectronicdevices 104 have a uniform and accurate height because the gap G₁between the dies 110 and the substrate 160 is based on the diameter D₃of the spacer elements 134. Another advantage of this feature is thatthe spacer elements 134 are expected to eliminate or at least inhibitthe electrical shorting which can occur when the electrical couplers 120collapse and spread during reflow.

C. Additional Embodiments of Methods for Manufacturing MicroelectronicDevices

FIGS. 3A-3E illustrate stages in another embodiment of a method formanufacturing a plurality of microelectronic devices in accordance withthe invention. For example, FIG. 3A is a top plan view of a microfeatureworkpiece 200, and FIG. 3B is a schematic side cross-sectional view ofthe workpiece 200 taken substantially along line 3B-3B in FIG. 3A.Referring to both FIGS. 3A and 3B, the illustrated workpiece 200 isgenerally similar to the workpiece 100 described above with reference toFIG. 2A. For example, the workpiece 200 includes a substrate 108 (FIG.3B), a plurality of dies 210 formed in and/or on the substrate 108, anda plurality of electrical couplers 120 attached to correspondingterminals 116 (FIG. 3B) on the dies 210. The illustrated workpiece 200,however, includes a plurality of discrete volumes of flowable material230 arranged in an array on corresponding dies 210. The individualvolumes of flowable material 230 include a binder 132 (FIG. 3B) and aplurality of spacer elements 134 (FIG. 3B) disposed within the binder132. The spacer elements 134 are sized to provide a minimum gap betweenthe dies 210 and the external members to which the dies 210 aresubsequently attached. In the illustrated embodiment, the volumes offlowable material 230 are placed on the active side 112 at each cornerof the individual dies 210. In other embodiments, such as the embodimentdescribed below with reference to FIGS. 4A and 4B, the volumes offlowable material 230 can be arranged on the workpiece 200 in otherconfigurations.

FIG. 3C is a schematic side cross-sectional view of the workpiece 200after forming an underfill layer 238 on the active side 112 of the dies210. The underfill layer 238 protects the dies 210 from moisture,chemicals, or other contaminants and may partially or completely coverthe electrical couplers 120 and/or the volumes of flowable material 230.In other embodiments, the underfill layer 238 may not be deposited ontothe workpiece 200, but rather underfill material may be introduced intothe gap between the dies 210 and a support member after attaching thedies 210 to the support member. In additional embodiments, the dies 210may not include an underfill layer. In either case, the workpiece 200can be cut along lines C-C to singulate the individual microelectronicdies 210.

FIG. 3D is a schematic side cross-sectional view of a microelectronicdevice assembly 202 including the singulated microelectronic dies 210arranged in an array on a support member 260. The illustrated supportmember 260 can be generally similar to the support member 160 describedabove with reference to FIG. 2B. For example, the support member 260includes a plurality of contacts 164, a plurality of pads 168, and aplurality of traces 169 electrically coupling the contacts 164 tocorresponding pads 168. The individual dies 210 are placed on thesupport member 260 by pressing the volumes of flowable material 230 andthe underfill layer 238 against the first side 162 of the support member260 with the electrical couplers 120 aligned with corresponding contacts164.

FIG. 3E is a schematic side cross-sectional view of the microelectronicdevice assembly 202 after reflowing the electrical couplers 120 tomechanically and electrically connect the terminals 116 to the contacts164. During reflow, the weight of the dies 210 may cause the heatedelectrical couplers 120 to collapse such that the dies 210 move towardthe support member 260 in the direction T. The movement of the dies 210spreads the volumes of flowable material 230, and at least some of thespacer elements 134 are sandwiched between the active side 112 of thedies 210 and the first side 162 of the support member 260. These spacerelements 134 inhibit further movement of the dies 210 in the direction Tand space the dies 210 apart from the support member 260 by a gap G₁.After reflowing the electrical couplers 120, a casing 170 is formed overthe dies 210, a plurality of conductive members 180 are attached tocorresponding pads 168, and the assembly 202 can be cut along lines D-Dto singulate a plurality of individual microelectronic devices 204.

D. Additional Embodiments of Microfeature Workpieces With FlowableMaterial

FIG. 4A is a schematic top plan view of a microfeature workpiece 300 inaccordance with another embodiment of the invention. FIG. 48 is aschematic side cross-sectional view of the workpiece 300 takensubstantially along line 4B-4B in FIG. 4A. The illustrated workpiece 300is generally similar to the workpiece 200 described above with referenceto FIGS. 3A and 3B. For example, the workpiece 300 includes a substrate108 (FIG. 4B), a plurality of dies 210 formed in and/or on the substrate108, and a plurality of electrical couplers 120 attached tocorresponding terminals 116 (FIG. 4B) on the dies 210. The illustratedworkpiece 300, however, includes a plurality of discrete volumes offlowable material 330 arranged in strips generally corresponding to theline of terminals 116 and electrical couplers 120 on each die 210. Thevolumes of flowable material 330 include a binder 132 (FIG. 4B) and aplurality of spacer elements 134 (FIG. 4B) disposed within the binder132. The spacer elements 134 are sized to provide a minimum gap betweenthe dies 210 and the external members to which the dies 210 aresubsequently attached. Although in the illustrated embodiment thevolumes of flowable material 330 cover the electrical couplers 120, inother embodiments the volumes of flowable material 330 may notcompletely cover the electrical couplers 120.

E. Additional Embodiments of Microelectronic Devices Including StackedDies

FIG. 5A is a schematic side cross-sectional view of a microelectronicdevice assembly 402 in accordance with another embodiment of theinvention. The device assembly 402 is generally similar to the assembly102 described above with reference to FIG. 2B. For example, theillustrated assembly 402 includes a support member 160, a plurality offirst dies 410 carried by the support member 160, a plurality of firstelectrical couplers 120 a extending between the terminals 116 of thefirst dies 410 and corresponding contacts 164 on the support member 160,and a flowable material or underfill layer 130 disposed between thefirst dies 410 and the support member 160. In the illustratedembodiment, however, the individual first dies 410 further include aplurality of conductive through-wafer interconnects 117 extendingbetween the active side 112 and the backside 114.

The illustrated microelectronic device assembly 402 further includes aplurality of second dies 210 attached to the backside 114 ofcorresponding first dies 410, a plurality of second electrical couplers120 b attached between the terminals 116 of the second dies 210 andcorresponding interconnects 117 in the first dies 410, and a pluralityof discrete volumes of flowable material 230 disposed between the firstand second dies 410 and 210. The volumes of flowable material 230 can beformed on the active side 112 of the second dies 210 or the backside 114of the first dies 410 before the second dies 210 are attached to thefirst dies 410. In either case, the underfill layer 130 and the volumesof flowable material 230 include a plurality of spacer elements 134 a-b,respectively, for providing a minimum gap between the differentcomponents. In other embodiments, the assembly 402 can further includean underfill layer between the first and second dies 410 and 210.

FIG. 5B is a schematic side cross-sectional view of the microelectronicdevice assembly 402 after reflowing the first and second electricalcouplers 120 a-b. During reflow, the weight of the first and second dies410 and 210 causes the first and second electrical couplers 120 a-b tocollapse such that the first and second dies 410 and 210 move toward thesupport member 160 in the direction T. The movement of the first dies410 spreads the underfill layer 130, and at least some of the spacerelements 134 a are sandwiched between the active side 112 of the firstdies 410 and the first side 162 of the support member 160. These spacerelements 134 a inhibit further movement of the first dies 410 in thedirection T and space the first dies 410 apart from the support member160 by a gap G₁. The movement of the second dies 210 spreads the volumesof flowable material 230, and at least some of the spacer elements 134 bare sandwiched between the active side 112 of the second dies 210 andthe backside 114 of the first dies 410. These spacer elements 134 binhibit further movement of the second dies 210 in the direction T andspace the first and second dies 410 and 210 apart by a gap G₂. Afterreflowing the first and second electrical couplers 120 a-b, a casing 470is formed over the dies 210 and 410, a plurality of conductive members180 are attached to corresponding pads 168, and the assembly 402 can becut along lines E-E to singulate a plurality of individualmicroelectronic devices 404.

One feature of the microelectronic devices 404 illustrated in FIG. 5B isthat the spacer elements 134 b are positioned outboard the secondelectrical couplers 120 b. One advantage of this feature is that thespacer elements 134 b prevent die tilt in which the distance between thefirst and second dies 410 and 210 varies across the devices 404. Dietilt can cause problems with molding, testing, and other post-reflowprocesses. For example, if the second die 210 is not parallel with thefirst die 410, the “high side” of the second die 210 may be exposedafter forming the casing 470.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. For example, many of the elements ofone embodiment can be combined with other embodiments in addition to orin lieu of the elements of the other embodiments. Accordingly, theinvention is not limited except as by the appended claims.

I claim:
 1. A microelectronic device at an intermediate stage ofprocessing, comprising: a microelectronic die having an integratedcircuit and a plurality of terminals operably coupled to the integratedcircuit; a plurality of metal connectors deposited on correspondingterminals, wherein the metal connectors have a first dimension beforebeing reflowed such that the metal connectors project from the die by afirst distance before the metal connectors are reflowed; and a flowablematerial disposed on the die and about the metal connectors, theflowable material includes a binder and a plurality of spacer elementsdistributed generally uniformly throughout the binder, the plurality ofspacer elements having a second dimension less than the first dimensionof the metal connectors before the metal connectors are reflowed suchthat after the metal connectors are reflowed the spacer elements areconfigured to space the die apart from a support member by a seconddistance corresponding to the second dimension of the spacer elements.2. The microelectronic device of claim 1 wherein: the metal connectorscomprise a plurality of solder balls having a first diameter; the spacerelements comprise a plurality of dielectric spherical members having asecond diameter of about 40% to about 70% of the first diameter of themetal connectors; the spherical members are distributed generallyuniformly throughout the flowable material; and the flowable materialfurther comprises at least one of an underfill material or a fluxcompound.
 3. The microelectronic device of claim 1 wherein the seconddimension of individual spacer elements is about 40% to about 70% of thefirst dimension of the metal connectors.
 4. The microelectronic deviceof claim 1 wherein the spacer elements comprise a plurality ofdielectric members.
 5. The microelectronic device of claim 1 wherein theindividual spacer elements have a dimension greater than 37 microns. 6.The microelectronic device of claim 1 wherein the flowable material isdisposed in discrete volumes arranged in an array on the die.
 7. Themicroelectronic device of claim 1 wherein the metal connectors comprisea plurality of solder balls electrically coupled to correspondingterminals.
 8. A microelectronic device at an intermediate stage ofprocessing, comprising: a microelectronic die having an integratedcircuit and a plurality of terminals operably coupled to the integratedcircuit; a plurality of metal connectors deposited on correspondingterminals, wherein the metal connectors have a first dimension beforebeing reflowed such that the metal connectors project from the die by afirst distance before the metal connectors are reflowed; and a flowablematerial disposed on the die and about the metal connectors, wherein theflowable material includes a plurality of glass spheres having a seconddimension less than the first dimension of the metal connectors beforethe metal connectors are reflowed such that after the metal connectorsare reflowed the glass spheres are configured to space the die apartfrom a support member by a second distance corresponding to the seconddimension of the glass spheres.
 9. A microelectronic device at anintermediate stage of processing, comprising: a microelectronic diehaving an integrated circuit and a plurality of terminals operablycoupled to the integrated circuit; a plurality of metal connectorsdeposited on corresponding terminals, wherein the metal connectors havea first dimension before being reflowed such that the metal connectorsproject from the die by a first distance before the metal connectors arereflowed; and a flowable material covering at least some of theterminals on the die and being disposed on the die and about the metalconnectors, wherein the flowable material includes a plurality of spacerelements having a second dimension less than the first dimension of themetal connectors before the metal connectors are reflowed such thatafter the metal connectors are reflowed the spacer elements areconfigured to space the die apart from a support member by a seconddistance corresponding to the second dimension of the spacer elements.10. A microelectronic device at an intermediate stage of processing,comprising: a microelectronic die having an integrated circuit and aplurality of terminals operably coupled to the integrated circuit; aplurality of metal connectors deposited on corresponding terminals,wherein the metal connectors have a first dimension before beingreflowed such that the metal connectors project from the die by a firstdistance before the metal connectors are reflowed; and a flowablematerial disposed on the die and about the metal connectors, wherein theflowable material includes a no-flow underfill and a plurality of spacerelements having a second dimension less than the first dimension of themetal connectors before the metal connectors are reflowed such thatafter the metal connectors are reflowed the spacer elements areconfigured to space the die apart from a support member by a seconddistance corresponding to the second dimension of the spacer elements.11. A microelectronic device at an intermediate stage of processing,comprising: a microelectronic die having an integrated circuit and aplurality of terminals operably coupled to the integrated circuit; aplurality of metal connectors deposited on corresponding terminals,wherein the metal connectors have a first dimension before beingreflowed such that the metal connectors project from the die by a firstdistance before the metal connectors are reflowed; and a flowablematerial disposed on the die and about the metal connectors, wherein theflowable material includes a flux compound and a plurality of spacerelements having a second dimension less than the first dimension of themetal connectors before the metal connectors are reflowed such thatafter the metal connectors are reflowed the spacer elements areconfigured to space the die apart from a support member by a seconddistance corresponding to the second dimension of the spacer elements.12. A microelectronic device at an intermediate stage of processing themicroelectronic device, comprising: a microelectronic component havingan active side and a plurality of terminals on the active side; aplurality of electrical couplers attached to corresponding terminals andprojecting from the microelectronic component, the individual electricalcouplers having a first dimension before bonding the electrical couplersto corresponding contacts of a support member; and a flowable materialdisposed on the active side of the microelectronic component beforebonding the electrical couplers to the corresponding contacts of thesupport member, the flowable material including a no-flow underfill anda plurality of spacer elements having a second dimension less than thefirst dimension of the electrical couplers.
 13. The microelectronicdevice of claim 12 wherein the individual spacer elements are sized tospace the microelectronic component apart from the support member afterattaching the microelectronic component to the support member.
 14. Themicroelectronic device of claim 12 wherein the spacer elements comprisea plurality of dielectric members distributed generally uniformlythroughout the flowable material.
 15. A microfeature workpiece at anintermediate stage of processing the microfeature workpiece, comprising:a plurality of microelectronic dies; a plurality of electrical couplersarranged in discrete arrays that are electrically coupled tocorresponding microelectronic dies, wherein individual electricalcouplers have a first dimension before bonding the electrical couplersto corresponding contacts of a support member; and a flowable materialdisposed on the microelectronic dies before bonding the electricalcouplers to the corresponding contacts of the support member, theflowable material including spacer elements being distributed generallyuniformly throughout the flowable material and having a second dimensionless than the first dimension of the electrical couplers.
 16. Themicrofeature workpiece of claim 15 wherein the individual spacerelements have a second dimension of about 40% to about 70% of the firstdimension of the electrical couplers.
 17. The microfeature workpiece atan intermediate stage of processing the microfeature workpiece,comprising: a plurality of microelectronic dies; a plurality ofelectrical couplers arranged in discrete arrays that are electricallycoupled to corresponding microelectronic dies, wherein individualelectrical couplers have a first dimension before bonding the electricalcouplers to corresponding contacts of a support member; and a flowablematerial disposed on the microelectronic dies before bonding theelectrical couplers to the corresponding contacts of the support member,the flowable material including a no-flow underfill and a plurality ofspacer elements having a second dimension less than the first dimensionof the electrical couplers.
 18. The microfeature workpiece of claim 17wherein: the individual microelectronic dies comprise a plurality ofterminals on which corresponding electrical couplers are deposited; andthe flowable material is disposed in discrete volumes covering at leastsome of the terminals on corresponding dies.
 19. The microfeatureworkpiece of claim 17 wherein the flowable material is disposed in alayer covering multiple dies.
 20. The microfeature workpiece of claim 15wherein the flowable material is disposed in discrete volumes arrangedin arrays on corresponding microelectronic dies.